Conventionally, transaction for which an application deadline to purchase a product is set is known in electronic commerce. A form of such transaction includes, for example, an auction, group purchase and a time sale. To purchase a product, it is necessary to bid on, place an order and apply for the product by the deadline set in advance. In this transaction form, service which reminds a user to apply for purchase by an application deadline is provided in some cases. For example, at a website of electronic commerce, the user can register a favorite product in, for example, a list referred to as a “watch list”. When the application deadline to purchase the product registered in the watch list nears, an electronic mail which is referred to as a remind mail (reminder mail) is sent to the user registered the product in the watch list. In case of, for example, an auction, an end date and time of the auction is described in the remind mail as the application deadline. The user can learn that the application deadline to purchase the product registered in the watch list nears by reading this remind mail.
Conventionally, a send timing of this remind mail is, for example, determined in advance a predetermined time before the application deadline, or can be set by the user. Meanwhile, Patent Literature 1 discloses a technique of, at a system side, setting a send timing of remind mail for product sales. More specifically, a product sales system disclosed in Patent Literature 1 sends a remind mail a little before a consumption cycle of the product passes based on a shipping date of the product ordered in the past from a client and a consumption cycle of the product.